In Midrash Tanhuma, we learn from a passouk:
ואתן לך ארץ חמדה (ירמ' ג יט), ארץ שנתחמדו לה כל גדולי עולם
"And I will give you a pleasant (wanted) land" – A land which all the great people wanted.
The midrash goes on to explain how each of our forefathers had a special connection to this land, thus showing that the "great people" refer to Avraham, Yitzhak and Yaacov.
Everyone knows that the first mitzvah commanded to Avraham Avinu was to leave his family behind and to go to the land of Israel.
וַיֹּאמֶר יְהוָה אֶל-אַבְרָם, לֶךְ-לְךָ מֵאַרְצְךָ וּמִמּוֹלַדְתְּךָ וּמִבֵּית אָבִיךָ, אֶל-הָאָרֶץ, אֲשֶׁר אַרְאֶךָּ. וְאֶעֶשְׂךָ, לְגוֹי גָּדוֹל, וַאֲבָרֶכְךָ, וַאֲגַדְּלָה שְׁמֶךָ; וֶהְיֵה, בְּרָכָה.
Now the LORD said unto Abram: 'Get thee out of thy country, and from thy kindred, and from thy father's house, unto the land that I will show thee. And I will make of thee a great nation, and I will bless thee, and make thy name great; and be thou a blessing. (Bereishit 12:1-2)
From these pssoukim, we can see two things: First of all, we see the first relation between one of our forefathers, Avraham, and the land of Israel. Secondly, we can clearly see that the greatness of our Nation is fully developed only on our land – The land of Israel. Many centuries later, the Kuzari explained this concept by comparing Klal Israel to a plant and explained that different plants need different soils in order to grow properly. For Klal Israel to grow properly and for our potential to come out fully as a Blessing for the whole world, we need to be based in the Land of Israel.
Afterwards, Abraham was commanded a second thing with relation to the Holy Land:
קוּם הִתְהַלֵּךְ בָּאָרֶץ, לְאָרְכָּהּ וּלְרָחְבָּהּ: כִּי לְךָ, אֶתְּנֶנָּה.
Arise, walk through the land in the length of it and in the breadth of it; for unto thee will I give it.' (Bereshit 13:17)
For a nice explanation on this passage, I suggest reading what I wrote here from my Rav, Rav Mordechai Elon Shli"ta. Chaz"al in Baba Batra explain that the reason he walked through is that by walking through the land, Avraham made it easier for his sons to take over. In other words, Avraham's walking was not simply meaningful to his time but rather was something which had eternal consequences on the ownership of the Jewish People on this land.
At the end of his life, Avraham finally got to Jerusalem, although it was during a very tough challenge – Akeidat Itzhak. In Pirkei DeRabbi Eliezer, we are taught that even as they were getting close to the mountain of Mount Moriah (Jerusalem), they already recognized the holiness of that place. When they got there, we are told that God himself told them that this is the place in which Avraham gave sacrifices, where Kain and Ebel brought sacrifices and where Noah and his sons also brought sacrifices. It is not a temporary place but rather a place which is inscribed in eternity.
In Hebron, Avraham, for the first time, bought a piece of land from the Land of Israel. In the Torah, the negotiations between Avraham and Efron are detailed very meticulously. The Ibn Ezra explains that the reason for that is that God wanted to show us how important the land of Israel is to show how much space the Torah dedicates to the buying of a piece of land there.
From all these events we see that at the source of the Jewish Nation, our oldest forefather Avraham Avinu, we already have many mentioned of a special connection between Klal Israel and Eretz Israel.
